[FIX] developer/reference/cli: --dev=replica

Introduced by odoo/odoo#195280 in saas-18.1

Author: Julien00859

content/developer/reference/cli.rst

@@ -436,6 +436,10 @@ Developer features
 
     * ``werkzeug``: display the full traceback on the frontend page in case of exception
 
+    * ``replica``: simulate :option:`db_replica_host` but connect to the same datbase server as
+      :option:`db_host`, this makes it possible to test read-only features without the need to setup
+      a replicated database.
+
 
 .. _reference/cmdline/server/http: